This is a U.S. national stage of application No. PCT/DE99/00631, filed on Mar. 3, 1999. Priority is claimed on that application and on the following application:
Country: Germany, Application No.: 198 15 154.3, Filed: Mar. 27, 1998.
1. Field of the Invention
The invention relates to a base of a metallurgical vessel having a direct-current arc device whose cathode projects into the vessel and in whose fire-resistant lining on the base at least one anode is arranged, one end of which, passing through the vessel wall, touches metallic melt located in the vessel, and the other end of which can be connected to cooling fluid supply sources and is attached in an electrically insulated manner to the vessel wall via holding elements.
2. Discussion of the Prior Art
DE 40 26 897 A1 discloses a metallurgical vessel having a vessel base which has a fire-resistant lining in which the base electrode of a direct-current arc furnace is arranged. A holding device is detachably attached to the casing of the vessel, isolated by insulation. The holding device in this case comprises a flanged tube which is arranged coaxially with respect to the electrode center and can be screwed to the metallurgical vessel.
The electrode, which passes through the furnace wall, makes contact with the melt located in the vessel. During operation, the head area of the electrode is melted. Since this is the lowest point in the furnace vessel, at which the melt is located, the thinner liquid and heavier melt components also gather here. Defects in the fire-resistant material can lead to connections of the liquid thread between the electrode and the metal casing of the vessel. This causes damage or destruction to the furnace vessel in the region of the base electrode, due to electrical flashovers.
The invention is based on the aim of providing a base of a metallurgical vessel having a direct-current arc device, in which the occurrence of electrical flashovers in the vessel base is prevented by simple design means.
According to the invention, the passage of the anode through the metallic base of the furnace vessel is designed as an outlet channel. For this purpose, a sleeve is provided which sheaths that part of the anode which projects into the vessel and in the process is placed at a distance sufficiently far away from the anode that low melting-point metals can flow out of the vessel without being impeded. The sleeve is in this case formed from a material which does not conduct electric current, preferably from ceramic.
The head of the sleeve, which faces the vessel interior, is designed as a collecting screen, and in this case has a conically diverging shape. In one advantageous refinement, the sleeve comprises at least two parts, with the first part having a cylindrical shape and the second part having a conically opening funnel shape away from a separation point in the direction of the vessel interior.
In a further advantageous embodiment, a sleeve which is composed of a fire-resistant ramming mass and extends in an extension of the funnel-shaped second part of the sleeve is provided in the fire-resistant lining. The sleeve formed from the ramming mass in this case provides the function of drainage and ensures that all the thin-liquid metal is passed to the sleeve even when the wear of the anode is relatively severe.
The distance xcex94r of the outlet channel between the anode and the tubular holding element of the anode and the sleeve is 0.5 to 2 mm. This distance is sufficient to prevent the normal melt from flowing out of the vessel base.
A collecting apparatus is arranged underneath the base, in order to collect the thin-liquid metal, such as lead, flowing out via the outlet channel.
In one particularly simple construction in design terms, the anode is held by a clamping ring which is separated via insulation and is arranged underneath the furnace base. The insulation is held in a positively locking manner as a simple ring by the furnace base and, in the process, is at a distance from the anode forming an outlet channel.